<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>元素的属性</title>
  <style>
    .front{
      color: red;
      font-weight: 900;
    }
  </style>
</head>
<body>
  <a href='https://xxx.net'>云课堂</a>
  <p class="front">前端</p>
  <p>后端</p>
  <p>测试</p>
</body>
</html>